that equates to a potential specific energy density of 3050 Wh/kg (around 19 times normal li-ion battery performance), handily trumping even the possibly-snazzy new lithium-sulphur tech which BASF have just jumped into. The scope is plainly there to achieve the five to tenfold storage boost that Professor Bruce is aiming at.

On discharge, Li+ from the electrolyte and e- from the external circuit combine with O2 from the air, the process is reversible. We have demonstrated evolution of O2 on charging. Capacities as high as 855 mAhg-1 (based on the total mass of the cathode plus the additional mass of O2) have been achieved and values of 1220 mAhg-1 are, in principle, possible.

Both of these are very impressive if true. 2-4x density is really all we need in practical circumstances. That's enough for ~500-1000 miles on a Roadster sized 450kg pack or ~250-500 on a 225kg pack.

With the claimed densities of these kind of pack, range can greatly exceed what is even possible in most gasoline cars (though it'll take a very long time to charge full). There are so many applications where this kind of density is useful beyond just EVs.

IBM Aims for a Battery Breakthrough 300 to 500 miles on a single charge

A consortium led by IBM hopes to develop lithium-air batteries that will power electric vehicles for 300 to 500 miles on a single charge Link
By Steve Hamm

"Eager to place itself at the forefront of technology considered crucial to transportation's future, Big Blue is throwing its weight behind batteries.

On June 23, IBM announced a multiyear effort to increase the performance of rechargeable batteries by a factor of 10. The aim is to design batteries that will make it possible for electric vehicles to travel 300 to 500 miles on a single charge, up from 50 to 100 miles currently. "We want to see if we can find a radically different battery technology," says Chandrasekhar "Spike" Narayan, who manages the Science & Technology Organization at IBM Research's Almaden lab in San Jose, Calif.

To do that, IBM (IBM) is leading a consortium that will create batteries using a combination of lithium and oxygen rather than the potentially combustible lithium-ion mix that now dominates advanced consumer electronics and early electric-vehicle batteries. The new batteries could be used to store energy in electric grids as well.

IBM is also eager to reclaim U.S. leadership in battery tech from Asia. While many of the original breakthroughs for the batteries that power today's laptop computers and cell phones happened in the U.S., those batteries now come primarily from Japan and Korea.

Industry leaders have called for just this kind of concerted effort amid concern that the U.S. will miss out on one of the most important technology shifts in history—the switch from gasoline to electricity as the primary power source for light vehicles. The worry is that the U.S. will trade its current dependency on the Middle East for oil with a new dependency on Asia for vehicle batteries. "We lost control of battery technology in the 1970s," laments Andy Grove, former chairman of chip giant Intel (INTC). "Battery technology will define the future, and if we don't act quickly it will go to China and Japan."

With theoretical densities of 3050 Wh/kg I wonder if it even makes sense to build these batteries as rechargeable kind. A cheap (to manufacture) zinc-air battery should be lightweight enough to be easily swapped at a charging station (providing a convenient central location for recycling purposes). The battery then becomes a commodity (and a business opportunity for progressive energy companies). What drivers get out of this is all the benefits of EV (the "grin") at low upfront cost, reasonable operating expenses and "refueling" convenience. Plus, there is choice: those who produce their own energy and use EV primarily for commuting can invest in rechargeable batteries for everyday purposes, but still have access to "commodity" battery infrastructure for long-distance trips and those unexpected moments.

Very low power density is another constraint of the Lithium-air battery. Unlike the high power providers of chemistries such as Lead-acid, current densities of Lithium-air can be as much as 1,000 times lower in order to extract the maximum amount of energy

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In terms of calendar life:

Reversability of the reaction to allow electrical recharge of Lithium-air is possible. Despite classifying the Lithium-air cell as a primary battery, the literature does include data on the performance of a rechargeable form, researched by Abraham, et. al.2 When the liquid electrolyte is replaced with a polymer electrolyte, the reaction of the lithium directly with oxygen forms lithium peroxide which can reoxidized to oxygen with externally applied current. This has been found to have major barriers in Zinc-air, so starting with the primary version of Lithium-air simplifies the goal tremendously.

Not really ... With more and more "news" of vaporware (EEStor and hydrogen fuel cells being chief offenders) polluting the infosphere, I feel more and more distraction from areas where real progress is taking place.

Who cares about subtle machinations of EEStor hyping their fancy [mildly useful] barium-titanate powder, when a real industrial research organization is most positioned to bring us the ultimate battery to the table:

The newly developed lithium-air cell with alkaline aqueous electrolyte gel has a discharging capacity of approximately 9000 mAh/g when it is discharged in the air at a discharge rate of 0.1 A/g. The charging capacity is about 9600 mAh/g. These values are considerably larger than the reported values of conventional lithium-air batteries (700 - 3000 mAh/g). Furthermore, by using an alkaline aqueous solution in place of an alkaline water-soluble gel, continuous discharging up to 20 days at the discharge rate of 0.1 A/g in the air has been realized. The discharge capacity of the cell was approximately 50,000 mAh/g (shown in Fig. 3).

Lithium air sounds really nice, and it has HUGE potential ... but there are still many kinks to work out. For example,

very low power density--

Very low power density is another constraint of the Lithium-air battery. Unlike the high power providers of chemistries such as Lead-acid, current densities of Lithium-air can be as much as 1,000 times lower in order to extract the maximum amount of energy.

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and doesn't like cold weather--

...the performance of Lithium-air varies by a factor of 5 over the -20°C to +40°C range

Now I'm sure these little issues can be resolved by keeping the batteries temperature-conditioned like the Roadster already does, and by paralleling with some Li-Ion batteries to supply the power while Li-Air batteries supply the energy.

Lithium air sounds really nice, and it has HUGE potential ... but there are still many kinks to work out. For example, very low power

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Indeed a discharge rate of .1 A/g at 3V equals power density of just 30 W/kg -- 10x weaker than lithium ion. The paper does not specifically mention whether tests were conducted at atmospheric pressure, but perhaps increasing pressure could result in higher current flow.

Now I'm sure these little issues can be resolved by keeping the batteries temperature-conditioned like the Roadster already does, and by paralleling with some Li-Ion batteries to supply the power while Li-Air batteries supply the energy.

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Or trickle charge an ultra-capacitor, some of which have power density of 6KW/kg.

Indeed a discharge rate of .1 A/g at 3V equals power density of just 30 W/kg -- 10x weaker than lithium ion. The paper does not specifically mention whether tests were conducted at atmospheric pressure, but perhaps increasing pressure could result in higher current flow.

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Did you just invent an EV supercharger? :smile:

Seriously, though, to generate the ~190kW that the Roadster uses, you'd need over 6000 kg of batteries! You would, presumably, use some kind of power buffer (like an ultracap) to cover for bursts, but you'd still need the main battery to provide the long-haul average power. At 250Wh/mile and 60 m/h, you need 15kW sustained, which would still be 500kg of batteries at 30 W/kg. That's somewhat bigger than the Roadster's battery, and still kind of on the weak side.

That is, I think to be useful in cars, they need a big improvement in power density.

Seriously, though, to generate the ~190kW that the Roadster uses, you'd need over 6000 kg of batteries! You would, presumably, use some kind of power buffer (like an ultracap) to cover for bursts, but you'd still need the main battery to provide the long-haul average power. At 250Wh/mile and 60 m/h, you need 15kW sustained, which would still be 500kg of batteries at 30 W/kg. That's somewhat bigger than the Roadster's battery, and still kind of on the weak side.

That is, I think to be useful in cars, they need a big improvement in power density.

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Well, I goofed on the order of magnitude (1 kg = 10^3 g), which means that .1 A/g translates into 300 W/kg, not 30. This level is presumably comparable to power output of lithium-ion cells currently employed in Roadster's ESS, so make that "power-brick" a 50 kg (instead of 40) for 15 kW on the go recharge of high power [low energy density] main traction battery. This looks like the game changer many were looking for (or did I goof with numbers somewhere again?)

Another way to look at it is that to deliver 190kW you'd need 633kg of the things.

633kg leads to 95MWh, which even with 'real world' power use is over 300,000 miles...

EDIT - so this felt a little too good to be true and here is why:

Having had time to read the linked article (as opposed to relying on the quotes above) I've seen there is some 'cheating' going on with the numbers. The energy density they are quoting is for the cathode only.

Comparison of cathode discharging capacity with that of conventional lithium ion battery.
mAh per 1 gram of cathode.

It felt slightly wrong given that the scaling up I did earlier based on this chart came out at ~50000 miles per charge, whereas the calculation from scratch came out at >300,000 miles.

Thinking about it, this can be verified by taking the 150mAh/g figure they have for Li-ion and working out Wh/kg, which comes out at 555Wh/kg. The alarm bells should be ringing, as the number for available batteries is under 200Wh/kg (2.775 times less).

So if you divide the 300,000 miles number by 2.775 (=108108) and then the ratio of the above pack to the Roadster's approximate mass of 18650 cells (633/320), you get 54,652 miles. Given some of the uncertainties in the information available, that's pretty close.

It's not clear, but that 2.775 divider also probably applies to the power density, so we are definitely back to the li-ion/capacitor based buffer to get peak power. But interestingly, it actually doesn't specify that 0.1A/g is the maximum discharge rate.

Still, this is an awesome achievement - I'd be interested to see the paper they presented in March for more details.

The plan from the Japanese researchers calls for an electric car driver to exchange one type of electrolyte in a battery cell for a new air electrode when the battery runs low.

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I have no interest in a battery that I can't charge cheaply at home. It negates one of the great benefits of an EV, low cost overnight home charging and never having to stop at a "gas" station or being tied into a single "fuel" source or provider.